1. Field of the Invention
The present invention relates to an operating unit for an endoscopic treatment tool.
2. Description of the Prior Art
An endoscopic treatment tool generally includes a treatment mechanism for applying medical or surgical treatment to a human body, an operating unit distanced from the treatment mechanism, and a connecting wire through which the treatment mechanism is remotely operated by the operating unit. The operating unit has a cylindrical body provided with a first finger-retaining portion, and a slider slidably supported on the cylindrical body and provided with a second finger-retaining portion. The slider is connected to the connecting wire. By moving the slider relative to the cylindrical body using an operator's thumb retained on the first finger-retaining portion and the operator's index and middle fingers retained on the second finger-retaining portion, the connecting wire is moved by the same amount as the relative movement between the slider and the cylindrical body, to thereby operate the treatment mechanism.
Some endoscopic treatment tools require large movement of connecting wires in order to operate treatment mechanisms. For example, a front loop wire type treatment tool such as a high-frequency snaring tool and a basket type recovery tool are such types of tools. During the medical or surgical treatment using the endoscopic treatment tool of this type, the operator must spread his hand to increase a distance between his thumb and his index and middle fingers as much as possible as shown in FIG. 7, which hinders smooth operation of the tool.
In contrast, some other endoscopic treatment tools require fine movement of connecting wires to operate treatment mechanisms. For example, biopsy forceps having a pair of closable forceps pieces as the treatment mechanism requires fine movement of the connecting wire so that the forceps pieces properly nip and cut a diseased tissue.